LTE radio access networks utilize base station nodes, referred to as evolved nodeBs (e-NodeBs or eNBs) for establishing bi-directional radio communications with mobile devices, referred to as user equipment (UEs), over an air interface. In practice each UE may be allocated one or more resource blocks (RBs) by the eNB for use in uplink (UE to eNB) communications and downlink (eNB to UE) communications. A resource block is a combination of symbols and subcarriers usable for carrying data between the eNB and the UE.
FIG. 1 illustrates an example of LTE resource blocks and assignment of the resource blocks to different users. In FIG. 1, one resource block is a unit of time and frequency that can be assigned to a user for uplink signal transmissions to an air interface device, such as an e-node B. Each resource block is divided into 7 symbols, represented by columns and 12 subcarriers, represented by rows. A resource element represented by an individual cell at the intersection of a symbol and a subcarrier. In the uplink direction, if a resource block is assigned to a particular UE, the resource block will carry data from the UE to the e-node B.
In the example illustrated in FIG. 1, all of the resource blocks are assigned to either User A or user B, which may correspond to UEs. These assignments are made by the e-Node B, communicated to the UEs in downlink signal transmissions, and instruct the UEs as to which resource blocks to use in uplink signal transmissions to the e-Node B. Each UE is responsible for decoding downlink signal transmissions from the e-Node B, identifying its resource block assignments, and transmitting to the e-Node B on the resource blocks to which the UE is assigned.
When the e-node B receives uplink signal transmissions from the UEs, the e-Node B monitors noise levels in the assigned resource blocks and uses the noise levels to make resource block assignments for subsequent uplink transmissions.
In a given uplink signal transmission, some resource blocks may be unassigned. For example, if one assigned resource block has a high level of noise, the e-Node B may deallocate assignment of the noisy resource block and assign another resource block to the UE. The process of monitoring and assigning resource blocks by the e-Node B is referred to as scheduling and is one of the most complex functions performed by an e-Node B.
Some uplink resource blocks may be unassigned in a particular uplink signal transmission. It is from these resource blocks that the e-Node B may assign to newly attached UEs or currently attached UEs that need new resource block assignments. Even though these unassigned resource blocks do not contain user data, the unassigned resource blocks may include noise. It is desirable to test how e-Node Bs schedule or assign UEs to unassigned resource blocks in the presence of noise in the unassigned resource blocks.
Accordingly, there exists a need for methods, systems, and computer readable media for testing air interface devices using emulated noise in unassigned RBs.